Sorry tinbum, but I didn't realise you'd replied to my earlier pm. Anyhow, what you've said makes sense in that the coils open out under compression and therefore is looser when fitted in the action. What is interesting though is just how many differing opinions there are on the subject.
I'll let you know how I get on.
Thanks again.
The more I shot it the smoother the rifle became, eventually I had to bring the power back down to were I'd set it at reassembly (10.7) I've since sold it to a mate and regularly give it the once over for him, he's put a further 2000+ pellets through it and it's still running 10.7 and shoots as smooth as butter !...
Ps, in fact it's that good I keep trying to twist his arm to sell it back to me !...
I always get a bit confused when it comes to comments on guide fit.
I understand that the spring will open up slightly when cocked.
I used to do at least one HW77 in winter as a project. I tried with the guides tight. Lower power and less consistent over the chrono. So I made them a slide in and out fit. More power ( so less spring ) and better consistency over the chrono. So I made mine a contact but slide fit.
Well i bought a drop in kit for my new HW95 and the spring guide is quite a loose fit on the supplied titan spring, almost as loose as the original guide was . Its also an inch shorter, but I guess this is to make room for the top hat? The spring ends are also just ground flat but not polished, i'm sure the spring ends were polished in the vmach kit i got a while back, kinda wishing i'd stumped up the extra now.
As long as it gets rid of the comically bad twang and brings it up to power i'll be happy.
OK, I understand what you're saying but isn't the point of 'tuning' a rifle, to get it to shoot as smoothly, consistently and as accurately as possible in the first place?
The tuning threads and guides I've read (and Iv'e read a few), all explain in detail the importance of burnishing, lubricating and polishing in order to allow all internal contact surfaces to work as freely and 'SMOOTHLY' as possible together which is key to getting the best out of the rifle. So... after doing all that why then go and fit something that's so tight and grabby, that it needs wearing in and takes away consistency and accuracy until it's worn sufficiently enough to fit properly?
If the guide had to wear itself down before the rifle improved it was obviously too tight a fit to start with, surely?
Depends on what you expect from a tune I spose, most rifles no matter how well tuned they are will still need to be run in and it's during this 'running-in' period that the rifle turns from a well tuned springer into one of the best rifles you've ever shot, when I first tuned my '95k' the difference between the standard rifle and the tuned one was unbelievable, what happened over the next few hundred shots left me pretty much lost for words and mine was just a basic home tune, leaves me wondering what a professional tuner is capable of !...
Well I got my HW95 back together and its better than it was but there's still a bit of twang. Not impressed at all, wish I had paid another £20 and got a Vmach kit now but these are given glowing reviews all over the various airgun forums so thought they were worth a try.
Could it just be that it needs a few shots through it all to bed in or if its twanging straight after fitting it wont get any better? I suspect its due to the loose fitting guide, although there might be room to fit a ptfe piston liner inside the steel liner which could help.
I make my spring guides to be a firm sliding fit, if it needs to be twisted in then it's too tight for me and I shave a little more off.
Almost every spring I have worked on has had a smaller opening, 0.1mm/0.2mm smaller than the overall ID, maybe it's caused by the finishing process but I always run a dremel round to inside of the opening.
Bob